Comparative replication of Hyphantria cunea nucleopolyhedrovirus in Spodoptera frugiperda and Lymantria dispar insect cell lines

Comparative Replication of Hyphantria cunea Nucleopolyhedrovirus in Spodoptera frugiperda and Lymantria dispar Insect Cell Lines In this study, replicational properties of Hyphantria cunea nucleopolyhedrovirus (HcNPV) were investigated in Spodoptera frugiperda (IPLB-Sf21) and Lymantria dispar (IPLB-Elta) cell lines. Infection was determined by formation of cytopathic effects (CPE), replication of viral DNA, transcription ofpolh gene, synthesis of viral structural proteins, production of extracellular virus, and formation of polyhedral inclusion body (PIB). It was observed that the CPEs determined by light microscopy in Sf21 cells appeared about 12 hours earlier as compared to those of LdElta cells. While polyhedral inclusion bodies formed at 36 h postinfection (p.i) in Sf21 cells, it was at 48 h p.i. in LdElta cells. Extracellular virus production determined according to cell culture infective dose 50% methods (TCID50) in LdElta cells formed about 12 h later when compared with Sf21 cells. Extracellular virus amounts produced in Sf21 and LdElta cells were calculated as 5.6 x 10 pfu/ml and 1.77 x 109 pfu/ml respectively, at 72 h p.i. It was determined that viral DNA replication defined by slot blot hibridization began at 12 h p.i. in both cells. Viral protein synthesis was determined by SDS-polyacrilamide gel electrophoresis (PAGE) and polyhedrine synthesis was observed at 12 h p.i. in both cells. Reverse transcriptase polymerase chain reaction (RT-PCR) results indicate that HcNPV-polh gene was transcribed at 10 h p.i. in both Sf2 1 and LdElta cells. Insecticidal effects of PIBs produced in cells were calculated as 51.9% and 65.38% on H. cunea and L. dispar larvae, respectively, by bioassay. Results indicate that the synthesis of macromolecules is 12 h late and production of extracellular virus is almost 3-fold low in LdElta cells compare to Sf21 cells. Key Words: Baculovirus, HcNPV, Sf21, LdElta, Virus Replication VII